1. Field of the Invention
The invention is related to automotive safety restraint systems and, in particular, a safety restraint system having a seat belt retractor driven by an electric motor for adjusting the seat belt about the operator.
2. Background of the Invention
The safety of the occupant of an automotive vehicle during a crash depends upon whether or not he or she is using a safety restraint system, and, if they are using one, is it properly adjusted. All to often, the occupant is wearing a safety restraint system, but it is not adjusted properly, reducing the effectiveness of the restraint system to prevent injury to the occupant.
Current three point safety restraint systems have a seat belt retractor which takes-up the slack in the seat belt after it is buckled up. These retractors normally have a spring motor exerting a torque tending to wind up the seat belt on the retractor's take-up spool. Unfortunately this torque snugs up the shoulder portion of the seat belt and maintains a constant pressure against the occupant's shoulder. For most people, this constant pressure on his or her shoulder is uncomfortable and annoying and therefore they tend not to use the safety restraint system. To eliminate this problem, the prior art teaches placing an adjustable stop on the seat belt which engages the shoulder guide to control the slack in the seat belt when it is snugged up by the retractor. Alternatively, the prior art teaches a tension eliminator built into the retractor which is capable of locking up the retractor's take-up spool to prevent the seat belt from exerting an uncomfortable force on the occupant's shoulder. These tension eliminators are normally set by pulling out a small amount of the seat belt setting a catch then letting the spring motor rewind the seat belt until the take-up spool locks up preventing further retraction of the seat belt.
The problem with the adjustable stop on the seat belt is that it has to be manually adjusted for each occupant. The adjustable stop is difficult to adjust, therefore it is frequently adjusted for the largest occupant and not changed thereafter. This provides excessive slack in the shoulder portion of the seat belt when worn by a smaller occupant and reduces the effectiveness of the safety restraint system. In a like manner, the tension eliminator is frequently set too loosely for the optimum effectiveness of the safety restraint system.
The invention is a safety restraint system in which the retractor is driven by an electric motor to properly adjust the seat belt for optimum protection of the occupant.